Integrated circuit dies contain an array of circuits that all require a very precisely controlled voltage and current. In some cases, the power supplied to each circuit is controlled with an external voltage regulator. In order to save space, part of the power supply is integrated onto the circuitry in the die. By using multiple on-die voltage regulators, the power to different parts of the circuitry can be controlled independently. This structure with multiple small voltage regulators can be used to reduce power in some sections that are not active or that are less active which saves energy overall. On-die voltage regulation can also be used to throttle voltages in real time and thereby provide active power management.
Some of the components for a power supply are not formed on the integrated circuit die. Passive components, such as inductors, transformers, and capacitors are difficult to form in the same process that is used to make transistors and may be too large to place on the die. Components formed outside of the die have more room and can be made to higher quality at less cost. For on-die voltage regulators, inductors can be mounted to a package substrate or embedded within a package substrate.
Integrated circuit dies are typically packaged for protection and to provide convenient external connections. The package has a package substrate that connects to one or more integrated circuit dies on one side and to a socket or printed circuit board on the other side. The integrated circuit dies may then be covered for protection. The substrate provides a convenient location to place passive devices with a simple connection pathway to the integrated circuit dies and to any external components.